Well, I'm of the opinion, from years of reading and studying, that we want to give our plants the
most light we can while continuing flowering. So I run my flowering light schedule at 13 ON / 11 OFF. Giving more darkness does not produce more trichomes, or resin, or speed up flowering. It only makes your plants grow less, which during flowering means grows fewer buds/resin.
I still go by what Rob Clarke said in Marijuana Botany: (paraphrasing)
studies have shown that half the amount of THC is produced when using 10 hours of light per day versus using 12 hours of light per day during flowering.
So for the past 8 years, I have run 13 hours ON.